MERS is thought to originate in camels.

Reuters/Geneva/Vienna

A Saudi woman suffering from Middle East Respiratory Syndrome (MERS) is assumed to have been infectious when she flew from Doha to Vienna on September 22, the World Health Organisation said on Thursday.

"The Austrian health authorities assume that the patient was infectious prior to and during the international flights. Follow-up with passengers on the flight is ongoing and personal data of the crew on the flight has been communicated to Qatar," a WHO statement said.

"All of the contacts identified in Austria have been informed about the disease and are being followed up by Austrian health authorities," it added.

Two close contacts were hospitalised with upper respiratory symptoms but Austria's Health Ministry said on Thursday they had tested negative for MERS.

A WHO spokesman said he did not know which airline the woman had flown on, or if there had been a stopover.

The 29-year-old had originally travelled by car from Afif in Saudi Arabia, via Riyadh, and had an upper respiratory infection and fever before she arrived in Austria.

She sought medical treatment in Austria on September 24 and was transferred to a private hospital on September 26, then on September 28 to a hospital specialising in highly infectious diseases, where she is in a stable condition.

At least 301 MERS-related deaths have been reported to WHO out of 853 laboratory-confirmed cases since the disease emerged in Saudi Arabia in 2012. But the European Centre for Disease Prevention and Control says 352 deaths have been reported to public health authorities worldwide, out of 887 confirmed cases.

A WHO Emergency Committee said on Wednesday that global defences against MERS needed to be strengthened, especially in Africa, before a likely seasonal resurgence of the disease next spring.

The disease is thought to originate in camels and, aside from travel-related cases, all MERS cases have been confined to the Arabian peninsula, Lebanon, Jordan and Iran.